Lattice location and electrical conductivity in Sb-implanted rutile

Abstract

Single crystals of ${\mathrm{TiO}}_{2}$ (rutile) were implanted with Sb ions applying fluences of 2\ifmmode\times\else\texttimes\fi{}${10}^{13}$/${\mathrm{cm}}^{2}$ to 5\ifmmode\times\else\texttimes\fi{}${10}^{16}$/${\mathrm{cm}}^{2}$ at 300 keV. The lattice location together with the ion range and damage distribution was measured using Rutherford-backscattering and channeling. The conductivity was measured as a function of temperature in the region between 6 and 300 K. Up to a dose of 5\ifmmode\times\else\texttimes\fi{}${10}^{15}$/${\mathrm{cm}}^{2}$ the Sb atoms were entirely substitutional on Ti sites as concluded from channeling measurements on 〈001〉- and 〈100〉-oriented ${\mathrm{TiO}}_{2}$ single crystals. A large increase of the conductivity \ensuremath{\sigma} was observed with increasing Sb dose, indicating a saturation behavior at about 30 ${\mathrm{\ensuremath{\Omega}}}^{\mathrm{\ensuremath{-}}1}$${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$. Between 40 and 293 K ln \ensuremath{\sigma} was proportional to ${\mathrm{T}}^{\mathrm{\ensuremath{-}}1\mathrm{/}2}$ for low doses, and proportional to ${\mathrm{T}}^{\mathrm{\ensuremath{-}}1\mathrm{/}4}$ for doses of 1\ifmmode\times\else\texttimes\fi{}${10}^{16}$ Sb/${\mathrm{cm}}^{2}$ and above, indicating that the transport mechanism is due to variable range hopping.